Node {0} is not reachable from node {1}. It is necessary that each cluster node can communicate each other cluster node by ...

Node {0} is not reachable from node {1}. It is necessary that each cluster node can 
    communicate each other cluster node by a minimum of one network path (though multiple paths
    are recommended to avoid a single point of failure). Please verify that existing networks
    are configured properly or add additional networks.